Photos that have gone viral show how Macron turned part of Trump's hand pale with a blood-squeezing grip when they met Friday on the sidelines of the G7 summit in Canada.

US President Donald Trump and French President Emmanuel Macron meet on the sidelines of the G7 Summit

La Malbaie, Canada: They once shook hands for an eye-watering 29 seconds, with neither man willing to show a hint of weakness. Now Emmanuel Macron has left a firm impression on Donald Trump in their latest squeezing contest.

Photos that have gone viral show how Macron turned part of Trump's hand pale with a blood-squeezing grip when they met Friday on the sidelines of the G7 summit in Canada.

Another picture appears to show the 71-year-old Trump wincing slightly as he struggles to get to grips with his 40-year-old counterpart.

The relationship between the two alpha males has been something of a rollercoaster ride since they first met last year, epitomized by their infamous handshake marathon in Paris during Bastille Day celebrations last July.

A thumbprint seen on Donald Trump's hand after a handshake with Emmanuel Macron at G7